Static mixing or motionless mixing apparatuses have been found to be effective for mixing together two or more fluid streams, to prepare a final mixed product. Such static or motionless mixers typically comprise a plurality of baffle-type elements disposed in a particular arrangement within a conduit, the baffle so arranged to provide for a plurality of subdivisions, as two or more streams are passed from the one to the other ends of the conduit containing the motionless mixer. A wide variety of various baffle designs of different shapes and geometric configurations has been proposed and used in connection with motionless mixers. For example, there are many motionless mixers available for the mixing of two or more low-viscosity liquids in turbulent flow; for example, with a Reynolds number of 10,000 or more, such as the mixing of water with hydrocarbons or the mixing of various acids with water in waste-water-treatment processes. While many various motionless mixer designs have been proposed, the overall performance of the mixers varies. The important criteria necessary in the selection of a motionless mixer include factors such as construction simplicity, manufacturing costs, the tendency of the mixer to plug or foul in operation, the pressure drop, the mixing effectiveness, and further the ability of the motionless mixer to pick up dense components from the bottom of a conduit and to mix such components into the main flow stream.
One motionless mixer, which employs semielliptical blade elements, is found in U.S. Pat. No. 3,652,061, which discloses a static mixing element of angularly disposed baffles, which baffles deflect and mix two or more fluid streams passing through the conduit. The individual blades of the baffle assembly are firmly attached to the interior surface of the surrounding conduit. A spiral-flow or mixing system is also described in U.S. Pat. No. 3,235,003, which discloses a plurality of various pairs of semielliptical baffle elements within a conduit, to induce helical flow, which patent relates primarily to mufflers and heat exchangers and the mixing of gases.